Most people know these mussels from what they find on the beach. At that point the mussel itself is gone, usually long eaten and all that remains is the shell with the pretty purple-blue color and the ridges that give it its’ name. Most people I show a dead one to know it is some type of mussel or incorrectly identify it as an oyster.
Most people also don’t know how much work these little mussels do and instead dream of them swimming in a good amount of butter. Butter won’t make up for their work in helping us.
Ribbed mussels are called bottom or filter feeders. They filter between 15 to 30 gallons of water a day. (There is some disagreement on this number. Basically, they filter a lot of water.) They live between 10 and 15 years. The math comes out to about 164,000 gallons of water that they filter in their life time. Remember, these numbers are for each individual mussel. If your local marsh or wetland holds a lot of mussels, that comes out to millions of gallons of water these mussels alone filter.
In the local marsh where I docent the tours, there are approximately one million of them. Someone needs to do a count as close as possible. They can be hard to see sometimes because they burrow down into the peat.
Also, people do come in and harvest them. One of the other volunteers noticed one wall of peat along one of the channels in the tidal pool we use was missing mussels. Upon further inspection one could see the indentations where the mussels had been.
If they are sealed shut, they are alive. They open a little during high tide to let the water in and filter it. Otherwise, they sit. Or do they?
This was the first year I had the opportunity to see juvenile mussels that look like blobs of jelly. I actually was on my hands and knees in the peat gently brushing it back.
They work together with the roots of spartina to hold the peat in place. The mussels go, spartina will soon follow. They live together in clumps. Foe protection? For mating?
I still have a lot to learn.